Avionics systems located on aircraft can be used to determine optimal or enhanced operating states of the aircraft based on various operating conditions and other parameters. For instance, data indicative of engine operating modes, flight path information, engine parameters (e.g., throttle setting, fuel flow, etc.), altitude, trim conditions, weight, and other operating parameters can be used to determine control variables, such as speed and/or altitude of an aircraft, to reduce the cost of conducting a flight. The cost of a flight can be defined, for instance, in terms of fuel consumption and/or time to achieve a flight range associated with the flight. The aircraft can be controlled in accordance with the determined operating variables to increase efficiency.
Conventional approaches for enhancing aircraft performance can include selecting operating commands that reduce direct operating cost based on a model of the aircraft performance. Known models can describe the nominal performance of the aircraft type. This approach can limit the level of efficiency that may be achieved because it fails to account for aircraft-specific variations, including but not limited to engine performance, slight differences in the shape of the vehicle body, and sensor errors. Additional limitations arise using models that fail to account for performance variations from flight-to-flight and un-modeled effects. Examples of these types of variations can include weight, center of gravity, surface cleanliness, and high-order terms in simplified engine models.
Analysis of existing performance modeling and optimization systems has confirmed and quantified some of the above limitations. For example, engine performance simulation using computer models has shown that existing models are typically either over-smoothed (do not include high-order effects) or are fitted experimentally to different flights (failing to account for aircraft-specific high-order effects.) In both cases, the existing models contain errors between the model and truth, which in some cases can amount to a full percentage point or more difference in operating cost when used to determine enhanced aircraft control. Other research has shown that various airframe effects may account for several percent differences in aerodynamic forces and moments. As such, a need remains for more accurate aircraft performance modeling for optimization that can achieve additional efficiency in aircraft operation.